Laser Wire Stripping

Do you find yourself needing to strip many ribbon cables? Isn’t it frustrating? Well, if you happen to own a laser engraver, this cool guide one of our tipsters sent us might just be up your alley.

The typical way to strip these is one by one, with a lot of swearing. Or, if you do it often, you might actually have the proper tool to strip them in one go. There is actually a third solution, and as it turns out, it’s one of the commercial ways it is done for accuracy, and it’s quite impressive. Here’s an entire imgur gallery of what some of the fancy stripping lasers are capable of — we particularly like number 3.

Anyway, if you do happen to have a laser cutter, it’s as simple as engraving a few lines, and setting up a jig to hold your ribbon. Take a pass on each side, and pull it off! There’s a video after the break, but it’s pretty self-explanatory. We can see this being super handy if you happen to be mass producing anything that requires ribbon cables!

I usually just press with a sharp knife on both sides of the cable and pull the end off. Works great, especially if the length is not critical so that you can redo it if you accidentally cut the wires.

Note: most insulation is PVC; when you laser cut it, it produces hydrochloric acid vapour… so make sure (1) your exhaust system is OK with that (i.e. it has activated carbon etc) and (2) you don’t mind your laser, extractor and other nearby objects rusting almost immediately.

Also make sure the wire isn’t oxidized to uselessness from the vapors, i usually have severe problems soldering ribbon cables where the insulation has been burnt, usually from previously heating the wire too much when putting on heatshrink.

Re: the vapours. Yes, it does stink a bit, and it will corrode anything it comes in contact with, but only really if you’re doing a lot. My own laser cutter is a cheap Chinese job so I’m not too worried about mucking up parts of it (the screws etc on the carriage are already rusted to hell anyway).

Re: oxidation of wire. Remember that the wire is still covered by the insulation, even after cutting, so the only part of the wire which could be affected is the very short bit underneath the cut. The rest will be in pristine condition.

I learnt my lesson a long time ago to not solder ribbon cables because
of long term reliability issues. Usually you’ll find broken connections
over time if you handle your board a lot. Insulation Displace Connectors
or crimped connectors are the proper way to terminate a connection.

When you solder the wire, solder wicks into the multistrand wire and
makes it stiffer. Right at the junction between wire with and without
solder is where you will find a lot of mechanical stress when you flex
the cable. Ribbon cable has thin insulation, few strands and you don’t
provide stress relieve, so it is particularly prone to that.

tekkieneet, absolutely true. Teflon coated wire is worse; to get the teflon insulation to stick to the wire, they have to silver plate the wire first. This _really_ causes the solder to wick in the insulation… They make heat sink clamps to attempt to try to prevent this, but it is really tedious. Crimping is the only thing allowed on commercial aircraft…

But if you find yourself just having to solder ribbon cable, I just dip the cut end in a solder pot. The heat causes the insulation to shrink back just about right, and the wires end up being tinned at the same time.

You are also supposed to use hot wire stripper on teflon wire for
aircraft so that you don’t nick the wire strands on stripping.

I have a small roll of FEP ribbon cables. It is high temp, high flex,
abrasion resistant similar to Teflon. I use them when I don’t have
space/height for connectors. The insulation however is too tough for IDC
connectors designed for regular PVC insulation anyways. I breakout the
connections using SMT pads in a zig zag pattern to match 0.05″ pitch.
Because of the stiffness of that plastic and the pads are no longer
lined up, the cable doesn’t bend easily at the joint. The stress is now
distributed on the high flex cable itself.

Depending on the board, zip-ties can also be a solution (I did a clusterfuck ribbon cable mating breadboard for work once. The board had unused mounting holes so I ziptied the cables flat to the board, then wrapped the whole sucker in about a half mile of electrical tape). The point is to make it so that the weak point isn’t flexing at all.

Cool I guess, but how often are most people using ribbon cable without IDC connectors? I guess I have seen some boards with ribbon cable which was soldered, but they were few and far between, and probably could have been implemented with SIP connectors and a minor board redesign.

You’re right ;-) The application, in my case, was a last-minute design change – a customer wanted a D15 connector mounted on the rear panel instead of the front, where the PCB footprint was, so I soldered in a short length of ribbon cable going to the rear connector. I later found that you can get IDC to board connectors which I could’ve used, but I could only see ones in a DIP pinout, not a D pinout.

To be on the safe side, I smothered some hot-melt glue along the connections to try and give a little bit of strain relief.

Thanks – I did know about them, and I should really have used them for the panel mounted connectors, but I didn’t have time to order.

Those are all panel-mount connectors – what I was really after was an IDC connector which went to a PCB connector, but with the pins in a D layout rather than the normal DIP layout. I could then have used IDC connectors at both ends. However, you only seem able to get DIP connectors.

Some wire may have polyurethane based insulation, which, when heated, can liberate diisocyanate monomers, dimers, trimers and prepolymers, with the potential to cause or worsen asthma…. so… make sure the ventilation is adequate if you are going to burn off wire insulation. See also:
D P Paisley 1969 ‘Isocyanate hazard from wire insulation: an old hazard in a new guise’. Br J Ind Med. 1969 January; 26(1): 79–81. PMCID: PMC1008865

LOL, it sound like I am dead but I don’t know it yet..
Yeah I realized the hazard and I do use a carbon fume filter on my desk.
I have been dipping my cables to lead bath for about 25 years, and before that I use candle light to burn and soften the insulator.

“how often are most people using ribbon cable without IDC connectors?”

Myself I use ribbon cable as general purpose hookup wire. (my electronics all have grey wires now, but originally the ribbon cable was rainbow colored) I’m starting to switch to the 80 conductor ribbon cable now, too. But anyway I wanted to offer two tips. Use toe nail clippers to strip ribbons, use your fingernails to strip single conductors, and I run the soldered wire through a nearby hole in the PCB (if it doesn’t have one I make one using a jeweler’s screwdriver) or with perfboard the wires go right through the perforations (especially the thinner 80 cond. wire) and sometimes a dab of hot melt glue (which I melt with my soldering iron then wipe the tip clean)